(CNN)An explosion hit military vehicles at an intersection in the Turkish capital of Ankara on Wednesday evening, officials said, in what the military called a terror attack.

Twenty-eight people were killed and 61 others were injured, according to Deputy Prime Minister Numan Kurtulmus.

Photos:Explosion rocks Turkey's capital

Photos:Explosion rocks Turkey's capital

Firefighters work at the scene of a deadly explosion in Ankara, Turkey, on Wednesday, February 17. The explosion hit three military vehicles and a private vehicle near parliament buildings, reported Turkey's semiofficial Anadolu news agency.

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Photos:Explosion rocks Turkey's capital

An injured person receives medical treatment on February 17. The cause of the blast wasn't immediately available. But Ankara Gov. Mehmet Kiliclar said it may have been caused by a car bomb, according to Anadolu.

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Photos:Explosion rocks Turkey's capital

Twenty-eight people were killed and 61 others were injured in the blast, according to Deputy Prime Minister Numan Kurtulmus.

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Photos:Explosion rocks Turkey's capital

People react at the scene of the explosion.

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Photos:Explosion rocks Turkey's capital

A firefighter tries to put out the blaze.

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Photos:Explosion rocks Turkey's capital

Smoke billows from the blast site.

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The explosion hit three military vehicles and a private vehicle in central Ankara, near Turkish Parliament buildings, Turkey's semiofficial Anadolu news agency reported, citing Ankara Gov. Mehmet Kiliclar. The vehicles were stopped at a traffic light, the military said.

Authorities believe a bomb-laden vehicle caused the explosion, Kiliclar said, according to Anadolu.

Video aired on CNN Turk showed large flames reaching toward the night sky from an area on the ground. Lights from numerous emergency vehicles flashed nearby.

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No group has claimed responsibility.

"Our determination to respond in kind against such attacks against our unity and future from outside and inside is even more strengthened through such attacks," Turkish President Recep Tayyip Erdogan said in a statement. "Turkey will not hesitate to use its right to self-defense anytime, anywhere, and in all situations."

His thoughts were echoed by U.S. Defense Secretary Ash Carter.

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"We strongly condemn this cowardly attack which appears to have targeted buses carrying Turkish military personnel. We stand with our Turkish allies in the face of this horrific act, which only strengthens our resolve to deepen our ongoing cooperation in the fight against terrorism," he said.

Soner Cagaptay, a senior fellow at the Washington Institute for Near East Policy think tank, said that if it was a bomb attack, suspects could include ISIS or the PKK, the Kurdish militant separatists that Turkey considers a terrorist group.

"There's definitely many reasons why Turkish reaction is going to be fierce" if this was an attack, he said.